Plotting systems are used for a variety of output applications. These systems typically include a plotting surface onto which a plotting medium is located, a plotting pen residing on a printhead, and associated electronics for determining the interaction between the printhead and a fixed framework or grid structure. A digital data signal is typically derived to guide the position of the plotter printhead relative to the grid structure.
E. Speicher, Multiple Movement Marking Machine, U.S. Pat. No. 4,557,191 (Dec. 10, 1985) discloses a marking device for printing identification marks, which is "mounted for vertical and pivotal movement on the end of an upper arm. The upper arm is movable along a first axis in a horizontal plane to extend and retract the marking head assembly into and out of marking position.
The upper arm is movable relative to the carriage, and the carriage is movable on a beam to carry the upper arm together with the marking device to a preselected position with respect to the objects to be marked". While Speicher discloses a marking device that is "movable in a plurality of directions in a horizontal plane, as well as vertically and rotationally about a vertical axis and also movable in a lifting operation through an arcuate path", the marking device is limited in travel to the mechanical limitations of the upper arm and carriage.
P. LaCanfora, Photoplotter, U.S. Pat. No. 4,003,061 (Jan. 11, 1977) discloses a photoplotter which includes "an image-projecting system movable with respect to a photosensitive material at relatively fast and efficient speeds and over relatively large areas. The photoplotter comprises a coherent fiber optic bundle for transmitting an image from the image-defining objects to the image-projecting system. The image can be moved over selective portions of the photosensitive material by moving the image-projecting system parallel to the material and rotated by rotating one end of the fiberoptic bundle". While LaCanfora discloses a movable and rotatable image-projecting system, the mechanical system is subject to the mechanical limits of the large and cumbersome image-projecting system components. As well, the plotter output image is easily obscured by the plotting components while the plotting operation proceeds.
J. McClean, N. Campbell, and I. Reid, Ultrasonic Scanning System, U.S. Pat. No. 4,881,177 (Nov. 14, 1989) disclose an ultrasonic scanning system for testing large curved components, with "water jet probes caliper-mounted on the working arm of an industrial robot". The "instantaneous probe position on the surface of the work piece is computed from data on the starting position of the scanning movement of the probe, and the scanning velocity of the probe". While the disclosed ultrasonic scanning system is movable in a plurality of directions with respect to the analysis of a given workpiece, the motion and extent of travel for the system is subject to the mechanical limitations of the working arm of the robot.
B. Wilkinson, System for Automatically Inspecting a Flat Workpiece for Holes, U.S. Pat. No. 4,711,579 (Dec. 5, 1987) discloses an inspection system for automatically documenting and verifying the position and dimensions of holes in a flat sheet metal workpiece which includes "a transparent, light diffusing inspection table upon which the workpiece is laid". "A ball screw-driven yoke travels continuously along the inspection table in the Y direction and includes a bottom bar for positioning a plurality of optical sensor arrays above the table. The optical sensor arrays are responsive to the presence (or absence) of light energy which is diffused by the table". Data is read and stored in a microcomputer for subsequent display and/or print out. "Circuitry is provided to multiplex the optical sensor arrays so that each pixel thereof is subsequently read in order to provide data corresponding to hole locations in the X direction across the table. The position of the yoke on the ball screw provides data corresponding to hole locations in the Y direction". While the disclosed automatic inspection system is movable in one direction with respect to the analysis of a given flat workpiece, the motion and extent of travel for the system is subject to the mechanical limitations of the ball-screw driven yoke and bottom bar.
P. Vachris, and T. Rodby, Portable "T"-Configured X-Y Plotter, U.S. Pat. No. 5,072,410 (Dec. 10, 1991) disclose a portable, X-Y plotter capable of plotting on any sized medium and work surface, which comprises "a generally T-configured instrument transport assembly for controllably imparting a dual (XY) axis translation to an instrument (e.g. plotting pen) across a workpiece (paper) and controllably engaging the plotting pen with the paper during its translation. A first translation arm extends in a first axial direction, and is supportable at its opposite ends on a work surface. A second translation arm, which forms a vertical leg of the T, is couple through a T-joint coupler to the first translation arm, so that the second translation arm extends in a second axial direction. A plotting pen is mounted on the second translation arm for translational movement in the second direction. A dual stepper motor unit in the T-joint coupler drives a rack and pinion for the first arm and a drive belt for the pen. While the disclosed portable "T" configured X-Y plotter is movable in two directions with respect to a medium and work surface, and can controllably engage a plotting pen with respect to a medium during the translation of the plotting pen holder, the motion and extent of travel for the plotter is subject to the mechanical limitations of the translation arms. As well, the plotter output image is easily obscured by the plotting components while the plotting operation proceeds.
C. Schantz, Ink Jet Printhead Electrical Connections, European Patent Application. 94306270.3 (filed Aug. 25, 1994) discloses a scanning head printer that includes a battery that is onboard a reciprocating printhead for providing power necessary for printing onto a medium. In a second embodiment, the drive signals for firing ink from the scanning printhead are transmitted in a wireless fashion. The scanning printhead can be free of restrictive cables that link the printhead to stationary circuitry. "A stationary primary coil may be employed for inductive coupling to a recharge coil that is mounted for movement with the printhead and the onboard battery, thereby permitting recharging of the battery when the printhead is in a rest position" . While the disclosed printhead electrical connections provide a printhead that uses onboard power for printing to a medium, and for receiving drive signals, the motion and extent of travel for the plotter is subject to the mechanical limitations of the translation arm that the printhead travels across. As in other prior art systems, the plotter output image is easily obscured by the plotting components while the plotting operation proceeds.
The disclosed prior art systems and methodologies thus provide basic plotting systems, but fail to provide a plotter print head that is independent of the mechanical limitations of a fixed two-dimensional device, and also fail to provide a plotter printhead that does not obscure the plotter output image while the plotting operation proceeds. The development of such a robotic plotting system would constitute a major technological advance.